Minor simplification

Avoid typedefs
This makes the header simpler, and silences `hs-bindgen` notices about "squashed" typedefs.
2026-02-19 16:29:52 +00:00 · 2026-02-19 16:29:52 +00:00 · 2026-02-19 16:29:52 +00:00 · 2026-02-19 16:29:52 +00:00 · 2026-02-19 16:29:52 +00:00 · 2026-02-19 16:29:52 +00:00
11 changed files with 274 additions and 131 deletions
--- a/.gitignore
+++ b/.gitignore
@ -1,3 +1,4 @@
 dist*
 result
 target
+cabal.project.local*
--- a/cabal.project
+++ b/cabal.project
@ -1,13 +1,5 @@
 packages: .

-- TODO a total hack
-package garnet
-  extra-lib-dirs:
-    /home/gthomas/code/garnet/rust/target/release
-    /home/gthomas/code/garnet/rust/target/debug
-  extra-include-dirs:
-    /home/gthomas/code/garnet/rust
-
 -- https://well-typed.com/blog/2026/02/hs-bindgen-alpha
 -- Haskell.nix doesn't seem to like `tag: release-0.1-alpha`, which the blog post suggests
 -- so we specify the equivalent commit SHAs manually instead
--- a/exe/GarnetRs/Wrapped.hs
+++ b/exe/GarnetRs/Wrapped.hs
@ -6,6 +6,7 @@ module GarnetRs.Wrapped (
    hello,
    helloStruct,
    helloShape,
+    add,
 ) where

 import Data.ByteString
@ -21,15 +22,15 @@ data T = T
    , b :: Word8
    }
 convertT :: T -> Raw.T
-convertT T{a, b} = Raw.T{a = CBool $ fromBool a, b}
+convertT T{a, b} = Raw.T{a = fromBool a, b}

 data Shape
    = Circle CDouble
    | Rectangle CDouble CDouble
 convertShape :: Shape -> Raw.Shape
 convertShape = \case
-    Circle r -> Raw.Shape (Raw.Shape_Tag 0) $ Raw.set_shape_body_circle $ Raw.Circle_Body r
-    Rectangle w h -> Raw.Shape (Raw.Shape_Tag 1) $ Raw.set_shape_body_rectangle $ Raw.Rectangle_Body w h
+    Circle r -> Raw.Shape Raw.Circle $ Raw.set_shape_body_circle $ Raw.Circle_Body r
+    Rectangle w h -> Raw.Shape Raw.Rectangle $ Raw.set_shape_body_rectangle $ Raw.Rectangle_Body w h

 hello :: ByteString -> IO ()
 hello s = useAsCString s $ Raw.hello . unsafeFromPtr
@ -39,3 +40,6 @@ helloStruct = Raw.hello_struct . convertT

 helloShape :: Shape -> IO ()
 helloShape = Raw.hello_shape . convertShape
+
+add :: Int64 -> Int64 -> Int64
+add = Raw.add
--- a/exe/Main.hs
+++ b/exe/Main.hs
@ -9,3 +9,4 @@ main = do
    helloStruct T{a = False, b = maxBound}
    helloShape $ Circle 3.14
    helloShape $ Rectangle 10.0 5.0
+    putStrLn $ "3 + 4 = " <> show (add 3 4)
--- a/72
+++ b/72
@ -5,7 +5,12 @@ set -euo pipefail

 # Generate Haskell FFI bindings from Rust source code.
 #
-# Pipeline: cargo build -> cbindgen -> patch header -> hs-bindgen
+# Pipeline:
+#   1. cargo build       - build the Rust static library
+#   2. cbindgen           - generate a C header from the Rust source
+#   3. awk                - patch the header for hs-bindgen compatibility
+#   4. hs-bindgen-cli     - generate Haskell FFI modules from the C header
+#   5. cabal configure    - point Cabal at the Rust build artifacts
 #
 # Prerequisites: run inside the Nix dev shell (provides gcc, cabal, cbindgen, hs-bindgen-cli).

@ -25,59 +30,18 @@ cbindgen \
  --lang c \
  --crate garnet-rs \
  --output "$HEADER" \
+  --style tag \
  "$RUST_DIR"

 echo "  Raw header written to $HEADER"

 # --- Step 3: Patch the header for hs-bindgen compatibility ---
+#
+# cbindgen emits:    union { ... };       (anonymous)
+# hs-bindgen needs:  union { ... } body;  (named)
+# See: https://github.com/well-typed/hs-bindgen/issues/1649
 echo "=== Patching header ==="
-
-# Two patches are needed:
-#
-# Patch 1: Replace cbindgen's enum pattern with typedef + #defines.
-#   cbindgen emits:  enum Shape_Tag { Circle, Rectangle, }; typedef uint8_t Shape_Tag;
-#   hs-bindgen needs: typedef uint8_t Shape_Tag; #define Circle 0 ...
-#
-# Patch 2: Name anonymous unions inside structs.
-#   cbindgen emits:  union { ... };
-#   hs-bindgen needs: union { ... } body;
-
 awk '
-# State machine for enum->typedef+define transformation
-/^enum [A-Za-z_][A-Za-z0-9_]* \{$/ {
-    in_enum = 1
-    enum_name = $2
-    variant_count = 0
-    delete variants
-    next
-}
-in_enum && /^\};$/ {
-    # Next line should be: typedef <type> <enum_name>;
-    in_enum = 0
-    pending_enum = 1
-    next
-}
-in_enum {
-    # Collect variant names (strip trailing comma and whitespace)
-    v = $0
-    gsub(/^[[:space:]]+/, "", v)
-    gsub(/,[[:space:]]*$/, "", v)
-    if (v != "") {
-        variants[variant_count] = v
-        variant_count++
-    }
-    next
-}
-pending_enum && /^typedef [A-Za-z0-9_]+ / {
-    # Emit: typedef <type> <name>; then #define for each variant
-    print $0
-    for (i = 0; i < variant_count; i++) {
-        printf "#define %s  %d\n", variants[i], i
-    }
-    pending_enum = 0
-    next
-}
-
 # Name anonymous unions: }; at end of union block inside struct -> } body;
 /^  \};$/ && saw_union {
    print "  } body;"
@ -94,11 +58,11 @@ pending_enum && /^typedef [A-Za-z0-9_]+ / {
 echo "  Patched header at $HEADER"

 # --- Step 4: Derive system include paths for hs-bindgen's libclang ---
-echo "=== Detecting system include paths ==="
-
+#
 # hs-bindgen uses libclang directly, which doesn't know about NixOS's
 # non-standard include locations. We extract them from cpp -v and pass
 # all of them — extra paths are harmless.
+echo "=== Detecting system include paths ==="
 CLANG_OPTIONS=()
 while IFS= read -r dir; do
  CLANG_OPTIONS+=("--clang-option" "-isystem$dir")
@ -122,6 +86,16 @@ hs-bindgen-cli preprocess \
  "${CLANG_OPTIONS[@]}" \
  -I "$RUST_DIR" "$HEADER_NAME"

+# --- Step 6: Configure Cabal ---
+#
+# Point Cabal at the Rust static library and C header. This writes
+# cabal.project.local (gitignored) with absolute paths derived from
+# the current working directory, avoiding hardcoded paths in cabal.project.
+echo "=== Configuring Cabal ==="
+cabal configure \
+  --extra-lib-dirs="$RUST_DIR/target/debug" \
+  --extra-include-dirs="$RUST_DIR"
+
 echo "=== Done ==="
 echo "Generated Haskell bindings in $HASKELL_DIR/generated/"
 echo "Run 'cabal run' to test."
--- a/generated/GarnetRs.hs
+++ b/generated/GarnetRs.hs
@ -3,12 +3,12 @@
 {-# LANGUAGE DerivingStrategies #-}
 {-# LANGUAGE DerivingVia #-}
 {-# LANGUAGE DuplicateRecordFields #-}
-{-# LANGUAGE ExplicitForAll #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE MagicHash #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeFamilies #-}
@ -19,8 +19,7 @@
 module GarnetRs where

 import qualified Data.Array.Byte
-import qualified Data.Bits as Bits
-import qualified Data.Ix as Ix
+import qualified Data.List.NonEmpty
 import qualified Data.Primitive.Types
 import qualified Data.Proxy
 import qualified Foreign as F
@ -28,20 +27,20 @@ import qualified Foreign.C as FC
 import qualified GHC.Generics
 import qualified GHC.Ptr as Ptr
 import qualified GHC.Records
+import qualified HsBindgen.Runtime.CEnum
 import qualified HsBindgen.Runtime.HasCField
-import qualified HsBindgen.Runtime.Internal.Bitfield
 import qualified HsBindgen.Runtime.Internal.ByteArray
 import qualified HsBindgen.Runtime.Internal.HasFFIType
 import qualified HsBindgen.Runtime.Internal.SizedByteArray
 import qualified HsBindgen.Runtime.LibC
 import qualified HsBindgen.Runtime.Marshal
-import Data.Bits (FiniteBits)
+import qualified Text.Read
 import HsBindgen.Runtime.Internal.TypeEquality (TyEq)
-import Prelude ((<*>), (>>), Bounded, Enum, Eq, Int, Integral, Num, Ord, Read, Real, Show, pure)
+import Prelude ((<*>), (>>), Eq, Int, Ord, Read, Show, pure, showsPrec)

 {-| __C declaration:__ @struct T@

-    __defined at:__ @garnet_rs.h 6:16@
+    __defined at:__ @garnet_rs.h 6:8@

    __exported by:__ @garnet_rs.h@
 -}
@ -114,34 +113,86 @@ instance ( TyEq ty ((HsBindgen.Runtime.HasCField.CFieldType T) "b")
  getField =
    HsBindgen.Runtime.HasCField.fromPtr (Data.Proxy.Proxy @"b")

-{-| __C declaration:__ @Shape_Tag@
+{-| __C declaration:__ @enum Shape_Tag@

-    __defined at:__ @garnet_rs.h 11:17@
+    __defined at:__ @garnet_rs.h 11:6@

    __exported by:__ @garnet_rs.h@
 -}
 newtype Shape_Tag = Shape_Tag
-  { unwrap :: HsBindgen.Runtime.LibC.Word8
+  { unwrap :: FC.CUInt
  }
  deriving stock (GHC.Generics.Generic)
-  deriving stock (Eq, Ord, Read, Show)
-  deriving newtype
-    ( HsBindgen.Runtime.Marshal.StaticSize
-    , HsBindgen.Runtime.Marshal.ReadRaw
-    , HsBindgen.Runtime.Marshal.WriteRaw
-    , F.Storable
-    , HsBindgen.Runtime.Internal.HasFFIType.HasFFIType
-    , Data.Primitive.Types.Prim
-    , HsBindgen.Runtime.Internal.Bitfield.Bitfield
-    , Bits.Bits
-    , Bounded
-    , Enum
-    , FiniteBits
-    , Integral
-    , Ix.Ix
-    , Num
-    , Real
-    )
+  deriving stock (Eq, Ord)
+  deriving newtype (HsBindgen.Runtime.Internal.HasFFIType.HasFFIType)
+
+instance HsBindgen.Runtime.Marshal.StaticSize Shape_Tag where
+
+  staticSizeOf = \_ -> (4 :: Int)
+
+  staticAlignment = \_ -> (4 :: Int)
+
+instance HsBindgen.Runtime.Marshal.ReadRaw Shape_Tag where
+
+  readRaw =
+    \ptr0 ->
+          pure Shape_Tag
+      <*> HsBindgen.Runtime.Marshal.readRawByteOff ptr0 (0 :: Int)
+
+instance HsBindgen.Runtime.Marshal.WriteRaw Shape_Tag where
+
+  writeRaw =
+    \ptr0 ->
+      \s1 ->
+        case s1 of
+          Shape_Tag unwrap2 ->
+            HsBindgen.Runtime.Marshal.writeRawByteOff ptr0 (0 :: Int) unwrap2
+
+deriving via HsBindgen.Runtime.Marshal.EquivStorable Shape_Tag instance F.Storable Shape_Tag
+
+deriving via FC.CUInt instance Data.Primitive.Types.Prim Shape_Tag
+
+instance HsBindgen.Runtime.CEnum.CEnum Shape_Tag where
+
+  type CEnumZ Shape_Tag = FC.CUInt
+
+  toCEnum = Shape_Tag
+
+  fromCEnum = GHC.Records.getField @"unwrap"
+
+  declaredValues =
+    \_ ->
+      HsBindgen.Runtime.CEnum.declaredValuesFromList [ (0, Data.List.NonEmpty.singleton "Circle")
+                                                     , (1, Data.List.NonEmpty.singleton "Rectangle")
+                                                     ]
+
+  showsUndeclared =
+    HsBindgen.Runtime.CEnum.showsWrappedUndeclared "Shape_Tag"
+
+  readPrecUndeclared =
+    HsBindgen.Runtime.CEnum.readPrecWrappedUndeclared "Shape_Tag"
+
+  isDeclared = HsBindgen.Runtime.CEnum.seqIsDeclared
+
+  mkDeclared = HsBindgen.Runtime.CEnum.seqMkDeclared
+
+instance HsBindgen.Runtime.CEnum.SequentialCEnum Shape_Tag where
+
+  minDeclaredValue = Circle
+
+  maxDeclaredValue = Rectangle
+
+instance Show Shape_Tag where
+
+  showsPrec = HsBindgen.Runtime.CEnum.shows
+
+instance Read Shape_Tag where
+
+  readPrec = HsBindgen.Runtime.CEnum.readPrec
+
+  readList = Text.Read.readListDefault
+
+  readListPrec = Text.Read.readListPrecDefault

 instance ( TyEq ty ((HsBindgen.Runtime.HasCField.CFieldType Shape_Tag) "unwrap")
         ) => GHC.Records.HasField "unwrap" (Ptr.Ptr Shape_Tag) (Ptr.Ptr ty) where
@ -151,32 +202,31 @@ instance ( TyEq ty ((HsBindgen.Runtime.HasCField.CFieldType Shape_Tag) "unwrap")

 instance HsBindgen.Runtime.HasCField.HasCField Shape_Tag "unwrap" where

-  type CFieldType Shape_Tag "unwrap" =
-    HsBindgen.Runtime.LibC.Word8
+  type CFieldType Shape_Tag "unwrap" = FC.CUInt

  offset# = \_ -> \_ -> 0

 {-| __C declaration:__ @Circle@

-    __defined at:__ @garnet_rs.h 12:9@
+    __defined at:__ @garnet_rs.h 12:3@

    __exported by:__ @garnet_rs.h@
 -}
-circle :: FC.CInt
-circle = (0 :: FC.CInt)
+pattern Circle :: Shape_Tag
+pattern Circle = Shape_Tag 0

 {-| __C declaration:__ @Rectangle@

-    __defined at:__ @garnet_rs.h 13:9@
+    __defined at:__ @garnet_rs.h 13:3@

    __exported by:__ @garnet_rs.h@
 -}
-rectangle :: FC.CInt
-rectangle = (1 :: FC.CInt)
+pattern Rectangle :: Shape_Tag
+pattern Rectangle = Shape_Tag 1

 {-| __C declaration:__ @struct Circle_Body@

-    __defined at:__ @garnet_rs.h 15:16@
+    __defined at:__ @garnet_rs.h 16:8@

    __exported by:__ @garnet_rs.h@
 -}
@ -184,7 +234,7 @@ data Circle_Body = Circle_Body
  { radius :: FC.CDouble
    {- ^ __C declaration:__ @radius@

-         __defined at:__ @garnet_rs.h 16:10@
+         __defined at:__ @garnet_rs.h 17:10@

         __exported by:__ @garnet_rs.h@
    -}
@ -230,7 +280,7 @@ instance ( TyEq ty ((HsBindgen.Runtime.HasCField.CFieldType Circle_Body) "radius

 {-| __C declaration:__ @struct Rectangle_Body@

-    __defined at:__ @garnet_rs.h 19:16@
+    __defined at:__ @garnet_rs.h 20:8@

    __exported by:__ @garnet_rs.h@
 -}
@ -238,14 +288,14 @@ data Rectangle_Body = Rectangle_Body
  { width :: FC.CDouble
    {- ^ __C declaration:__ @width@

-         __defined at:__ @garnet_rs.h 20:10@
+         __defined at:__ @garnet_rs.h 21:10@

         __exported by:__ @garnet_rs.h@
    -}
  , height :: FC.CDouble
    {- ^ __C declaration:__ @height@

-         __defined at:__ @garnet_rs.h 21:10@
+         __defined at:__ @garnet_rs.h 22:10@

         __exported by:__ @garnet_rs.h@
    -}
@ -305,7 +355,7 @@ instance ( TyEq ty ((HsBindgen.Runtime.HasCField.CFieldType Rectangle_Body) "hei

 {-| __C declaration:__ @union \@Shape_body@

-    __defined at:__ @garnet_rs.h 26:3@
+    __defined at:__ @garnet_rs.h 27:3@

    __exported by:__ @garnet_rs.h@
 -}
@ -328,7 +378,7 @@ deriving via HsBindgen.Runtime.Marshal.EquivStorable Shape_body instance F.Stora

 __C declaration:__ @circle@

-__defined at:__ @garnet_rs.h 27:17@
+__defined at:__ @garnet_rs.h 28:24@

 __exported by:__ @garnet_rs.h@
 -}
@ -355,7 +405,7 @@ set_shape_body_circle =

 __C declaration:__ @rectangle@

-__defined at:__ @garnet_rs.h 28:20@
+__defined at:__ @garnet_rs.h 29:27@

 __exported by:__ @garnet_rs.h@
 -}
@ -403,7 +453,7 @@ instance ( TyEq ty ((HsBindgen.Runtime.HasCField.CFieldType Shape_body) "rectang

 {-| __C declaration:__ @struct Shape@

-    __defined at:__ @garnet_rs.h 24:16@
+    __defined at:__ @garnet_rs.h 25:8@

    __exported by:__ @garnet_rs.h@
 -}
@ -411,14 +461,14 @@ data Shape = Shape
  { tag :: Shape_Tag
    {- ^ __C declaration:__ @tag@

-         __defined at:__ @garnet_rs.h 25:13@
+         __defined at:__ @garnet_rs.h 26:18@

         __exported by:__ @garnet_rs.h@
    -}
  , body :: Shape_body
    {- ^ __C declaration:__ @body@

-         __defined at:__ @garnet_rs.h 29:5@
+         __defined at:__ @garnet_rs.h 30:5@

         __exported by:__ @garnet_rs.h@
    -}
--- a/generated/GarnetRs/FunPtr.hs
+++ b/generated/GarnetRs/FunPtr.hs
@ -10,6 +10,7 @@ import qualified GHC.IO.Unsafe
 import qualified GHC.Ptr as Ptr
 import qualified HsBindgen.Runtime.Internal.CAPI
 import qualified HsBindgen.Runtime.Internal.HasFFIType
+import qualified HsBindgen.Runtime.LibC
 import qualified HsBindgen.Runtime.PtrConst
 import Data.Void (Void)
 import GarnetRs
@ -41,6 +42,15 @@ $(HsBindgen.Runtime.Internal.CAPI.addCSource (HsBindgen.Runtime.Internal.CAPI.un
  , "{"
  , "  return &hello_shape;"
  , "}"
+  , "/* com_garnet_GarnetRs_get_add */"
+  , "__attribute__ ((const))"
+  , "int64_t (*hs_bindgen_bbabdbe61cd1eeb2 (void)) ("
+  , "  int64_t arg1,"
+  , "  int64_t arg2"
+  , ")"
+  , "{"
+  , "  return &add;"
+  , "}"
  ]))

 -- __unique:__ @com_garnet_GarnetRs_get_hello@
@ -55,7 +65,7 @@ hs_bindgen_faf62265b53521d3 =
 {-# NOINLINE hello #-}
 {-| __C declaration:__ @hello@

-    __defined at:__ @garnet_rs.h 32:6@
+    __defined at:__ @garnet_rs.h 33:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -75,7 +85,7 @@ hs_bindgen_0f8c37ef19b17a6d =
 {-# NOINLINE hello_struct #-}
 {-| __C declaration:__ @hello_struct@

-    __defined at:__ @garnet_rs.h 34:6@
+    __defined at:__ @garnet_rs.h 35:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -95,10 +105,30 @@ hs_bindgen_287ff3ac660f333b =
 {-# NOINLINE hello_shape #-}
 {-| __C declaration:__ @hello_shape@

-    __defined at:__ @garnet_rs.h 36:6@
+    __defined at:__ @garnet_rs.h 37:6@

    __exported by:__ @garnet_rs.h@
 -}
 hello_shape :: Ptr.FunPtr (Shape -> IO ())
 hello_shape =
  GHC.IO.Unsafe.unsafePerformIO hs_bindgen_287ff3ac660f333b
+
+-- __unique:__ @com_garnet_GarnetRs_get_add@
+foreign import ccall unsafe "hs_bindgen_bbabdbe61cd1eeb2" hs_bindgen_bbabdbe61cd1eeb2_base ::
+     IO (Ptr.FunPtr Void)
+
+-- __unique:__ @com_garnet_GarnetRs_get_add@
+hs_bindgen_bbabdbe61cd1eeb2 :: IO (Ptr.FunPtr (HsBindgen.Runtime.LibC.Int64 -> HsBindgen.Runtime.LibC.Int64 -> IO HsBindgen.Runtime.LibC.Int64))
+hs_bindgen_bbabdbe61cd1eeb2 =
+  HsBindgen.Runtime.Internal.HasFFIType.fromFFIType hs_bindgen_bbabdbe61cd1eeb2_base
+
+{-# NOINLINE add #-}
+{-| __C declaration:__ @add@
+
+    __defined at:__ @garnet_rs.h 39:32@
+
+    __exported by:__ @garnet_rs.h@
+-}
+add :: Ptr.FunPtr (HsBindgen.Runtime.LibC.Int64 -> HsBindgen.Runtime.LibC.Int64 -> IO HsBindgen.Runtime.LibC.Int64)
+add =
+  GHC.IO.Unsafe.unsafePerformIO hs_bindgen_bbabdbe61cd1eeb2
--- a/generated/GarnetRs/Safe.hs
+++ b/generated/GarnetRs/Safe.hs
@ -7,9 +7,11 @@ module GarnetRs.Safe where

 import qualified Foreign as F
 import qualified Foreign.C as FC
+import qualified GHC.Int
 import qualified GHC.Ptr as Ptr
 import qualified HsBindgen.Runtime.Internal.CAPI
 import qualified HsBindgen.Runtime.Internal.HasFFIType
+import qualified HsBindgen.Runtime.LibC
 import qualified HsBindgen.Runtime.PtrConst
 import Data.Void (Void)
 import GarnetRs
@ -35,6 +37,13 @@ $(HsBindgen.Runtime.Internal.CAPI.addCSource (HsBindgen.Runtime.Internal.CAPI.un
  , "{"
  , "  hello_shape(*arg1);"
  , "}"
+  , "int64_t hs_bindgen_1c0c71fa74c428a9 ("
+  , "  int64_t arg1,"
+  , "  int64_t arg2"
+  , ")"
+  , "{"
+  , "  return add(arg1, arg2);"
+  , "}"
  ]))

 -- __unique:__ @com_garnet_GarnetRs_Safe_hello@
@ -51,7 +60,7 @@ hs_bindgen_433ea2a26af4e593 =

 {-| __C declaration:__ @hello@

-    __defined at:__ @garnet_rs.h 32:6@
+    __defined at:__ @garnet_rs.h 33:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -75,7 +84,7 @@ hs_bindgen_51157946af5519c9 =

 {-| __C declaration:__ @hello_struct@

-    __defined at:__ @garnet_rs.h 34:6@
+    __defined at:__ @garnet_rs.h 35:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -101,7 +110,7 @@ hs_bindgen_7de06f1fd827ca60 =

 {-| __C declaration:__ @hello_shape@

-    __defined at:__ @garnet_rs.h 36:6@
+    __defined at:__ @garnet_rs.h 37:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -112,3 +121,35 @@ hello_shape ::
 hello_shape =
  \s0 ->
    F.with s0 (\s1 -> hs_bindgen_7de06f1fd827ca60 s1)
+
+-- __unique:__ @com_garnet_GarnetRs_Safe_add@
+foreign import ccall safe "hs_bindgen_1c0c71fa74c428a9" hs_bindgen_1c0c71fa74c428a9_base ::
+     GHC.Int.Int64
+  -> GHC.Int.Int64
+  -> GHC.Int.Int64
+
+-- __unique:__ @com_garnet_GarnetRs_Safe_add@
+hs_bindgen_1c0c71fa74c428a9 ::
+     HsBindgen.Runtime.LibC.Int64
+  -> HsBindgen.Runtime.LibC.Int64
+  -> HsBindgen.Runtime.LibC.Int64
+hs_bindgen_1c0c71fa74c428a9 =
+  HsBindgen.Runtime.Internal.HasFFIType.fromFFIType hs_bindgen_1c0c71fa74c428a9_base
+
+{-|
+
+  Marked @__attribute((const))__@
+
+__C declaration:__ @add@
+
+__defined at:__ @garnet_rs.h 39:32@
+
+__exported by:__ @garnet_rs.h@
+-}
+add ::
+     HsBindgen.Runtime.LibC.Int64
+     -- ^ __C declaration:__ @a@
+  -> HsBindgen.Runtime.LibC.Int64
+     -- ^ __C declaration:__ @b@
+  -> HsBindgen.Runtime.LibC.Int64
+add = hs_bindgen_1c0c71fa74c428a9
--- a/generated/GarnetRs/Unsafe.hs
+++ b/generated/GarnetRs/Unsafe.hs
@ -7,9 +7,11 @@ module GarnetRs.Unsafe where

 import qualified Foreign as F
 import qualified Foreign.C as FC
+import qualified GHC.Int
 import qualified GHC.Ptr as Ptr
 import qualified HsBindgen.Runtime.Internal.CAPI
 import qualified HsBindgen.Runtime.Internal.HasFFIType
+import qualified HsBindgen.Runtime.LibC
 import qualified HsBindgen.Runtime.PtrConst
 import Data.Void (Void)
 import GarnetRs
@ -35,6 +37,13 @@ $(HsBindgen.Runtime.Internal.CAPI.addCSource (HsBindgen.Runtime.Internal.CAPI.un
  , "{"
  , "  hello_shape(*arg1);"
  , "}"
+  , "int64_t hs_bindgen_20eb651f0a8faf48 ("
+  , "  int64_t arg1,"
+  , "  int64_t arg2"
+  , ")"
+  , "{"
+  , "  return add(arg1, arg2);"
+  , "}"
  ]))

 -- __unique:__ @com_garnet_GarnetRs_Unsafe_hello@
@ -51,7 +60,7 @@ hs_bindgen_2dfe97662a4d6377 =

 {-| __C declaration:__ @hello@

-    __defined at:__ @garnet_rs.h 32:6@
+    __defined at:__ @garnet_rs.h 33:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -75,7 +84,7 @@ hs_bindgen_29d823ada2bc7302 =

 {-| __C declaration:__ @hello_struct@

-    __defined at:__ @garnet_rs.h 34:6@
+    __defined at:__ @garnet_rs.h 35:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -101,7 +110,7 @@ hs_bindgen_b3f40a03f07eaa85 =

 {-| __C declaration:__ @hello_shape@

-    __defined at:__ @garnet_rs.h 36:6@
+    __defined at:__ @garnet_rs.h 37:6@

    __exported by:__ @garnet_rs.h@
 -}
@ -112,3 +121,35 @@ hello_shape ::
 hello_shape =
  \s0 ->
    F.with s0 (\s1 -> hs_bindgen_b3f40a03f07eaa85 s1)
+
+-- __unique:__ @com_garnet_GarnetRs_Unsafe_add@
+foreign import ccall unsafe "hs_bindgen_20eb651f0a8faf48" hs_bindgen_20eb651f0a8faf48_base ::
+     GHC.Int.Int64
+  -> GHC.Int.Int64
+  -> GHC.Int.Int64
+
+-- __unique:__ @com_garnet_GarnetRs_Unsafe_add@
+hs_bindgen_20eb651f0a8faf48 ::
+     HsBindgen.Runtime.LibC.Int64
+  -> HsBindgen.Runtime.LibC.Int64
+  -> HsBindgen.Runtime.LibC.Int64
+hs_bindgen_20eb651f0a8faf48 =
+  HsBindgen.Runtime.Internal.HasFFIType.fromFFIType hs_bindgen_20eb651f0a8faf48_base
+
+{-|
+
+  Marked @__attribute((const))__@
+
+__C declaration:__ @add@
+
+__defined at:__ @garnet_rs.h 39:32@
+
+__exported by:__ @garnet_rs.h@
+-}
+add ::
+     HsBindgen.Runtime.LibC.Int64
+     -- ^ __C declaration:__ @a@
+  -> HsBindgen.Runtime.LibC.Int64
+     -- ^ __C declaration:__ @b@
+  -> HsBindgen.Runtime.LibC.Int64
+add = hs_bindgen_20eb651f0a8faf48
--- a/rust/garnet_rs.h
+++ b/rust/garnet_rs.h
@ -3,34 +3,37 @@
 #include <stdint.h>
 #include <stdlib.h>

-typedef struct T {
+struct T {
  bool a;
  uint8_t b;
-} T;
+};

-typedef uint8_t Shape_Tag;
-#define Circle  0
-#define Rectangle  1
+enum Shape_Tag {
+  Circle,
+  Rectangle,
+};

-typedef struct Circle_Body {
+struct Circle_Body {
  double radius;
-} Circle_Body;
+};

-typedef struct Rectangle_Body {
+struct Rectangle_Body {
  double width;
  double height;
-} Rectangle_Body;
+};

-typedef struct Shape {
-  Shape_Tag tag;
+struct Shape {
+  enum Shape_Tag tag;
  union {
-    Circle_Body circle;
-    Rectangle_Body rectangle;
+    struct Circle_Body circle;
+    struct Rectangle_Body rectangle;
  } body;
-} Shape;
+};

 void hello(const char *c);

 void hello_struct(struct T t);

 void hello_shape(struct Shape s);
+
+__attribute__((const)) int64_t add(int64_t a, int64_t b);
--- a/rust/lib.rs
+++ b/rust/lib.rs
@ -22,7 +22,7 @@ extern "C" fn hello_struct(t: T) -> () {
    say_hello(&format!("{:?}", t))
 }

-#[repr(C, u8)]
+#[repr(C)]
 #[derive(Debug)]
 enum Shape {
    Circle { radius: f64 },
@ -33,3 +33,9 @@ enum Shape {
 extern "C" fn hello_shape(s: Shape) -> () {
    say_hello(&format!("{:?}", s))
 }
+
+/// cbindgen:prefix=__attribute__((const))
+#[unsafe(no_mangle)]
+extern "C" fn add(a: i64, b: i64) -> i64 {
+    a + b
+}
Author	SHA1	Message	Date
George Thomas	5d2ba1a217	Minor simplification	2026-02-19 16:29:52 +00:00
George Thomas	528cf7b8d7	Avoid typedefs This makes the header simpler, and silences `hs-bindgen` notices about "squashed" typedefs.	2026-02-19 16:29:52 +00:00
George Thomas	cb05afc21d	Use simpler tagged union translation Avoids the worst part of the header hack, and makes Haskell wrapper simpler.	2026-02-19 16:29:52 +00:00
George Thomas	604bc8cf2f	Mark pure function	2026-02-19 16:29:52 +00:00
George Thomas	6468f15d73	Use fixed-width integers	2026-02-19 16:29:52 +00:00
George Thomas	024b6aec87	Implement function with return value	2026-02-19 16:29:52 +00:00
George Thomas	40bb939302	Stick to Rust debug builds in shell to avoid C lib dir confusion	2026-02-19 16:29:52 +00:00
George Thomas	ddc8b9097d	Avoid absolute path hack	2026-02-19 16:29:52 +00:00
George Thomas	25875c7dc1	Move Haskell package to top level	2026-02-19 16:29:52 +00:00
George Thomas	2bab0ff94e	Rename Haskell.nix flake input	2026-02-19 16:29:52 +00:00
George Thomas	7d90990b74	Bump flake inputs	2026-02-19 16:29:52 +00:00
George Thomas	56370bb8a4	Reformat	2026-02-19 16:29:52 +00:00
George Thomas	b9e2e59174	Refactor Nix flake inputs	2026-02-19 16:29:52 +00:00
George Thomas	97a4f1c359	Disable dead code warning for whole Rust file	2026-02-19 16:29:52 +00:00
George Thomas	d8c12b5418	Call struct function with different arguments	2026-02-19 16:29:52 +00:00
George Thomas	0e54cccd74	Create manual high level wrapper	2026-02-19 16:29:52 +00:00
George Thomas	f1ec06fcca	Add Bash script dependencies to Nix shell	2026-02-19 16:29:52 +00:00
George Thomas	13b9324bc4	Simplify use sites by passing by value	2026-02-19 16:29:52 +00:00
George Thomas	5f1e49c4ce	Use ByteString	2026-02-19 16:29:52 +00:00
George Thomas	7e09c1d681	Add more complex data types	2026-02-19 16:29:52 +00:00
George Thomas	0a1911862f	Expose explicit C interface We drop the tools specifically designed for Haskell and Rust together, in favour of general tools for using each with C. Namely, we use Mozilla's `cbindgen` for generating header files from the Rust source, and Well-Typed's new `hs-bindgen` tool for generating Haskell from those header files. The Rust code here is essentially the result of expanding the old macro, then inlining and renaming internals. The most important thing here is that we're now relying solely on robust well-maintained tools.	2026-02-19 16:29:41 +00:00